$700 for a link placed on an on-topic PR6 page with 270 outbound links, or $275 for a link on an on-topic PR5 page with 23 outbound links? Both sites are .orgs, links come with memberships. Both memberships offer a certain limited amount of exposure to new clients.
Well, it's not really buying links per se...it's buying memberships to the non-profit organizations, and the links are just part of the membership. Since they are well regarded non-profits with a purpose other than selling links Google really wouldn;t have any way of knowing would it?